The present invention relates to a program zoom camera in which photographing range is changed corresponding to a distance of an object so that the object is printed in predetermined size.
It is conventionally known that a various of cameras in which photographing range can be set optionally. There are two ways to change the photographing range; one way is to change the focal length of a photographing lens, and the other way is to execute photographing without changing the focal length of the photographing lens, and at the same time, designate the range to be printed of a film and print only the designated range in printing. The latter way is called pseudo format camera or trimming camera and is described precisely in Japanese Laid-Open Patent Publication No. 54-26721.
Since the focal length of the photographing lens is not changed in the latter way, the range of a film to be exposed (so called photographing range) cannot be changed. Changed, though pseudo focal length is designated. It is noted that "photographing range" described in this specification indicates the range of which a photographer intends to photograph or the range revealed on a print. It does not always corresponding to the range exposed on a film. In those circumstances, in this specification, "change of photographing range" includes not only changing an exposure range but also changing the range to be printed, and further, the combination of the two ranges.
In such a camera where photographing range can be changed, it has been proposed that the size of the object be constantly printed in predetermined size by measuring distance from the camera to the object to be photographed and setting the photographing range according to the data of measured distance (for example, Japanese Laid-Open Patent Publication Nos. 1-44428 and 63-298231). This type of camera will be called a program zoom camera, and the change of photographing range according to the data of distance measuring will be called program zooming operation in this specification.
In a program zoom camera disclosed in Japanese Laid-Open Patent Publication No. 63-298231, it is designed that a range size to be printed which is designated in the pseudo focal length photographing (hereinafter referred to as trimming magnification), to is calculated automatically according to the data of object distance by selecting the predetermined print image.
Conventionally, when a moving object (object which is approaching or retreating from the camera) is photographed by using a program zoom camera, the size of the object image on a film is changed when a practical photographing is executed because of release time lag or the like. As a result, the size of the object to the photographing range differs from the predetermined size, especially when an object moving toward the camera is photographed under these conditions the the object often deviates from the scene to be photographed.